A method and test device for recognizing detecting whether a mass air flow meter of intake air of an internal combustion engine is defective is provided. In the method and device, a test procedure is executed using a pilot controller while a mixture controller that is used in non-test engine operation is deactivated. The pilot controller for the mixture of fuel and air in the respective cylinders outputs control values which, during normal operation of the internal combustion engine via the mixture control, are varied on the basis of a mixture deviation of the current mixture from a stoichiometric mixture. The engine is set to one or more different idling speeds and at each respective idling speed the mixture deviation is detected. If the detected mixture deviation(s) (i'lA.) satisfy a predetermined criteria thresholds, the air flow meter is identified as defective.

A controller for controlling an internal combustion engine includes an injection amount calculation portion that calculates a base injection amount, an injection amount correction portion that corrects the base injection amount to calculate first and second corrected injection amounts, and an injection count determination portion that determines first and second fuel injection counts, which are respectively a number of times fuel is injected from first and second fuel injection valves. When the first and second corrected injection amounts are respectively calculated using the same base injection amount, the injection count determination portion sets the first fuel injection count corresponding to the first corrected injection amount to be equal to the second fuel injection count corresponding to the second corrected injection amount.

Systems are provided for detecting a change in performance of an engine component. In one example, a system includes a first pressure sensor of a first exhaust manifold coupled to a first subset of cylinders of an engine, a second pressure sensor of a second exhaust manifold coupled to a second subset of cylinders of the engine, a passage coupling the first exhaust manifold to an intake manifold, and a controller configured to detect a change in performance of any cylinder of the engine based on frequency content from the first pressure sensor and from the second pressure sensor during both a first mode where no exhaust gas from the first exhaust manifold is provided to the intake manifold, and during a second mode where all exhaust gas from the first exhaust manifold is provided to the intake manifold, and adjust an operating parameter responsive to the change in performance.

Methods and systems are provided for controlling individual cylinder air-fuel ratio (AFR) in a combustion engine. In one example, a method may include measuring a high-frequency exhaust gas composition, parsing the measured high-frequency exhaust gas composition to determine a first cylinder-specific component of the high-frequency exhaust gas composition, estimating an air-fuel ratio (AFR) based on the first cylinder-specific component of the measured high-frequency exhaust gas composition, and correcting the estimated AFR by subtracting intercylinder exhaust gas interactions from the estimated AFR.

Methods and systems are provided for learning a cylinder-to-cylinder air variation. During conditions when a PFDI engine is operated in a port-injection only mode, prior to port fuel injection, a direct-injection fuel rail pressure may be lowered via direct-injection. Then, prior to a spark event in a port-injected cylinder, the direct-injector may be transiently opened to use the rail pressure sensor for estimating a cylinder compression pressure, and inferring cylinder air charge therefrom.

Method for the operation of an internal combustion engine having a plurality of cylinders (11 to detect misfires. An exhaust gas sensor at the exhaust gas of every cylinder of the internal combustion engine measures at least one actual exhaust gas value individually for the respective cylinder, and the respective measured actual exhaust gas value is compared with a reference exhaust gas value to determine at least one cylinder-specific deviation between the reference exhaust gas value and the actual exhaust gas value for each of the cylinders. It is determined for every cylinder based on the cylinder-specific deviation or based on every cylinder-specific deviation whether or not misfires are occurring at the respective cylinder.

A homogeneous charge compression ignition free-piston linear generator is disclosed. The linear generator includes a housing having cylinders at opposite ends. A double-ended piston assembly is to move linearly in the housing to convert kinetic energy of the piston assembly into electrical energy, and to enable conversion of electrical energy into kinetic energy of the piston assembly. Sensors measure one or more states of the cylinders and/or piston assembly, and a controller controls the linear generator based on the sensor data.

A system may include at least one engine bank including a plurality of fuel injectors. At least one exhaust temperature sensor is coupled to the engine bank(s). The exhaust temperature sensor(s) is configured to output at least one temperature signal regarding an exhaust temperature of the engine bank(s). A traction system is configured to output at least one electrical signal related to a power output of a vehicle. A control unit is coupled to the exhaust temperature sensor(s) and the traction system. The control unit is configured to receive the temperature signal(s) and the electrical signal(s). The control unit is configured to determine a mechanical and electrical health of the plurality of the fuel injectors by determining a temperature differential value of the temperature signal(s) and a power differential value related to the electrical signal(s), and analyzing a combination of the temperature differential value and the power differential value.

Methods and systems are provided for diagnosing a degraded fuel injector delivering undesired additional fuel in a variable displacement engine. In one example, a method includes, responsive to an indication of a cylinder air-fuel imbalance, deactivating a subset of cylinders of a multi-cylinder engine, performing a power balance test to determine an output of each cylinder after a duration of deactivation, and indicating that a deactivated cylinder has a degraded fuel injector responsive to the output being lower than a threshold output.

A system for detecting a fault condition in a valvetrain of an engine is configured to measure one or more operating parameters associated with the engine and determine if the operating parameters satisfy pre-defined corresponding boundary conditions. If so, a pair of values of at least one performance parameter is measured corresponding to measurement on a first and second bank of cylinders present on the engine. The difference between the pair of values is determined and used to compute at least one measure of variation for the at least one performance parameter in a time segment. If the at least one measure of variation for the at least one performance parameter exceeds a pre-defined limit for the engine, the valvetrain is flagged as faulty.